The present invention relates to a sensing device for and to be used in association with an adaptive optical system and being provided for ascertaining errors in the image of an imaged object, the optical system is assumed to include an element providing for optical phase corrections; moreover it is assumed that the optical system includes an entrance pupil subdivided into several subapertures for purposes of providing several individual images of the object whereby the individual subapertures are associated with optic-electrical detectors.
A device of the type to which the invention pertains and including generally the type mentioned above is described for example in U.S. Pat. No. 4,141,652. This kind of sensing device is also known as Hartmann sensor. A sensor of this type is provided for recognizing disturbing interferences in planar wavefronts or spherically curved wavefronts e.g. as emitted by a laser or by a point like light source as it occurs during propagation through the atmosphere. The known sensor operates on the basic principle that the aperture of the adaptive optic is to be subdivided into subapertures and their size is proportioned so that the respective optical interferences occuring therein become noticeable only as tilting of the respective optical axis. Herein the laser beam is for ex. acquired and ascertained by such a subaperture is focused upon the respectively associated quadrant detector and deviations of the image light spot from the optical axis as determined by the quadrant detector as an initial condition is measured. This then represents a kind of absolute measurement as far as tilting of the beam axis is concerned, such tilting being individually associated with the respective subaperture. It was found however that this procedure requires a very high expenditure in optical and mechanical accuracy and is, therefore, applicable only to the special cases of planar or spherical wavefronts as they are respectively produced e.g. by a laser beam or by a star.